U.S. Entered World War I
April 6, 1917
Disagreements in Europe over territory and boundaries, among other
issues, came to a head with the assassination of the Archduke
Ferdinand of Austria by a Serbian zealot on June 28, 1914. Exactly one month
later, war broke out. In 1915, the British passenger liner the
Lusitania was sunk by a German submarine, killing 128 Americans and
futher heightening tensions. By the end of 1915, Austria-Hungary,
Bulgaria, Germany, and the Ottoman Empire were battling the Allied
Powers of Britain, France, Russia, Italy, Belgium, Serbia, Montenegro
and Japan. In 1917, the U.S. entered the war. Germany formally
surrendered on November 11, 1918, and all nations agreed to stop fighting while the terms of peace were negotiated.